Prescription medication may be needed to treat some attacks by lice, which scientists say have now become "super" and resistant to over-the-counter treatments in California and 24 other states.
Researchers presented the head-scratching findings at the 250th National Meeting and Exposition of the American Chemical Society in Boston in August.
The study's author Kyong S. Yoon, an assistant professor at Southern Illinois University, identified products such as ivermectin and spinosad, both of which require prescriptions, as possible effective agents in killing the current breed of lice.
"It's a really, really serious problem right now in the U.S.," Yoon told Time.
Other states where lice populations developed a high level of resistance to common treatments included: Washington, Arizona, Texas, Kansas, Missouri, Arkansas, Minnesota, Wisconsin, Illinois, Indiana, Ohio, Kentucky, Tennessee, Alabama, Georgia, Florida, Georgia, South Carolina, North Carolina, Virginia, Maryland, Connecticut, Massachusetts, Rhode Island and Maine.
There's more bad news: there's no evidence that "nit pickers," the fine-toothed combs that some parents use, work to remove lice, Dr. Bernard Cohen, a professor of pediatrics and dermatology at the Johns Hopkins Children's Center, told TODAY.com.
"There have been a couple of nice studies showing that nit picking doesn't really work," he said.
An over-the-counter treatment should be used at least a few times spaced by a week or 10 days before it is declared a failure.
But if it does not work, and lice are still present, there are prescription medicines that are effective and safe, including ivermectin, spinosad and benzyl alcohol, Cohen said. A pediatrician or nurse practitioner should also make sure that your child actually does have lice, he said.
And if your children do get lice, it is not a sign that they are not well cared for, he said.
In fact, he said, “Head lice like you clean.”